Automatically adjustable centrifugal fan



June 10, 1958 c. M. BREMNER AUTOMTICALLY ADJUSTABLE CENTRIF'UGAL FANFiled Aug. 9, 195e 2 Sheets-Sheet 1 (NUEKTOQ.

C. M. BREMNER AUTOMATICALLY ADJUSTABLE CENTRIFUGAL. FAN

Filed Aug. 9, 1956 2 Sheets-Sheet 2 inited States Patent AUTOMATICALLYADJUSTABLE CENTRIFUGAL FAN Claude M. Bremner, Cranbrook, BritishColumbia, Canada, assignor to ivi. C. Marcotte, Hudson Bay,Saskatchewan, Canada Application August 9, 1356, Serial No. 603,051

il Claims. (Cl. 230--114) My invention relates tol new and usefulimprovemeiits in fans, particularly fans adapted to be used in agricultural machinery, such as threshing machines and combines, in which thefan directs Ia stream of air through various screens and the like inorder to lseparate chaff from grain, the principal object and essence ofmy invenautomatically increases the volume of air when the speed thereofdecreases and vice versa, thus enabling a larger volume of air to besent through the machine when, for example, it strikes a relativelyheavy stand of grainwhich slows `down the machine. Alternatively, whenthe machine strikes a relatively light stand of grain, the tendency isfor the machine to speed up, which normally would increase the volume ofair put out by the fan. However, with this device the volume of airautomatically decreases under these conditions, thus enabling much moreefficient separation to take place undera variety of conditions.

A still further object of my invention is to provide a device of thecharacter herewithin described which requires only .one setting, suchsettings being made by the operator while the `machine is running andwithout any danger attendent thereto. i f

A still further object of my invention is `to provide a device of thecharacter herewithin ydescribed which 'eliminates'the necessity forshutters and flaps and other `such means normally associated with fansof this nature for controlling the volume of air ldisplaced thereby.

Yet another object Aof my invention is to provide a device of thecharacter herewithin described which is relatively simple inconstruction, economical in manufacture, and otherwise well suited tothe -purpose for which it is designed.

With the foregoing objects in view. and such vother o'bjects `andadvantages as will vbecome apparent to those skilled in the art to whichthis invention relates as this specification proceeds, my inventionconsists essentially in the arrangement and construction of parts all ashereinafter more particularly described, reference being `had to theaccompanying .drawings in which:y

Figure l is a side sectional elevation 'of my device taken substantiallyalong the li-nes -1-1 of Figmre 2.

Figure 2 is a sectional elevation at right angles to Figure ltaken along`thelines 2-2of Figure 1.

Figure 3 is an enlarged partially sectioned of the trunnion gear and camper se.

In the drawings likeV characters of reference indicate correspondingparts in the Idiiferent Ifigures. t

Proceeding now to describe my invention Vin detail, it will be seen uponreference to the accompanying drawings that l'hayeillustrated a fanunit'collec'tively"desigelevation nated 1 mounted upon a drive shaft 2,which is journalled for rotation within bearings 3, it being understoodthat these bearings are supported by conventional structure, and thatthe fan unit i is normally surrounded by duct work also conventional incharacter in order to direct the air to where it is required.

The fan unit l comprises a spider collectively designated 4, whichincludes asupporting hub 5 secured to shaft 2 by means of set screws 6.A web 7 extends outwardly from the shoulder 5 and carries an annularcasing component 8, the purpose of which will hereinafter be described.

The casing S is vmade in two halves, 8 and S', joined together centrallyby means of lugs 9l and bolts 10, and -it will be noticed that the half8' of the casing includes enclosing flanges 11. Bearing apertures 12 areformed symmetrically around the perimeter of the casing land supportsfor partial rotation spindles or shafts 13, the ends l@ of which extendbeyond the sides of the casing.

Substantially rectangular planar fan blades 15 are providedwith securingbrackets i6 which terminate in bosses i7, said bosses engaging over theaforementioned ends i4 of the shaft i3 and are secured thereto by meansof set screws 1S.

Within the enclosure i9 formed by the casing 8 is situated what l defineas trunnion means takingthe form of a gear journalled for independentrotation upon shaft 2 by means of roller or ball bearings 2l. Meanscollectively designated 22 extend between this trunnion gear 20 and thefan blade shaft 14 for rotating said shaft within limits and in thisembodiment these means take the form of sector gears 23.V Y

Each .of these sector gears 23 is provided with a hub 24' by which it issecured to the shaft 13 medially along the length thereof and within anannular recess 25 formed when the halves S and 8' of the spider casingare secured together. The perimetrical portions 26 of the sector gearsare provided with teeth 27 engageablc with the teeth 28 of theaforementioned trunnion gear 20.

From a perusal'of the foregoing it will be appreciated that movement ofthe trunnio-n gear rotatively will cause corresponding angular movementof the fan blade 15 due to the engagement of the trunnion gear with thesector gears and it is to be appreciated that this movement is equaltoall fan blades situated upon the unit.

One face 29 o-f the trunnion gear 20 is provided with .a pair ofinclined cams 3b as clearly shown in Figure 3 and these cams areengageable byl means collectively desig. nated 3l adapted to be shiftedendwise upon shaft 2. The means 31 consist of a cylindrical housing 32surrounding shaft 2 and being splined thereto for limited endwisemovement, reference character 33 indicating the splines upon the shaft2. It will be appreciated that the inner bore of the housing 32 is alsovsplined to lengage splines 33 thus permitting the housing to berevolved by shaft 2 but also permitting endwise movement thereupon.

Adjacent the end 34 of the housing I have provided -a plurality ofrollers 35 journalled for rotation by means of bolts 36, it being seenthat the plane of rotation of these rollers is parallel to thelongitudinal axis of shaft 2. it will also be observed that theperimeters of these rollers are adapted to engage the aforementioned camupon the trunnion gear 2d.

It will therefore also be seen that endwise' movement of the housing 3lwill cause the rollers 35 to bea-r against the cam 30 thus causingrotation of the trunnion gear and hence ro-tation of the sector gearswhich will alter the angle of inclination of the fan blades l5 and'thatalso the reverse action will be true.

Means collectively designated 3S are provided to .control this rotativemovement of the trunnion gear 26 and take the form of an open-endedcylinder 39 mounted externally of the spider casing 4. A rod 40 isfreely slidable through this cylinder 39 but endwise movement of the rodin a leftward direction with reference to Figure l is restricted bymeans of apin 41 passing through the shaft and engaging within the end42 of the cylinder 39.

The end 43 of the rod is screw-threaded and passes through a ring 44which freely encircles an annular groove 45 formed upon the end 46 ofthe aforementioned housing 32. This groove'is made by providing ashoulder upon the housing and encircling the outer end of the shoulderwith sleeve 47 held in position by means of set screws 48.

The aforementioned end 43 of rod 40 is held in the desired position bymeans of clamped nuts 49 one upon each side of the ring 44 and theseclamp nuts together with the screw-threaded end 43 of the rod constitutea primary adjustment for the device as will hereinafter be described.

Within cylinder 39 is a relatively heavy duty coil spring 50 reactingbetween pin 41 on the rod and an adjusting nut l screw-threadablyengageable within the other end 52 of the cylinder so that tighteningthc adjusting nut 51 inwardly increases the tension on the spring S0reacting upon the rod 40.

In operation, the initial setting of the rod 40 is made by means of theaforementioned locking nut 49 so that for example the pressure of spring50 forces the rod 40 leftwardly with reference to Figure l thus rotatingthe trunnion gear 20 so that the fan blades are in the position shown inFigure 2.

The fan, which is adapted to rotate in the direction of arrow 3displaces a given volume of wind for a given speed of rotation and theadjusting nut 51 should be adjusted so that the pressure generated bythe air against the blades causes them to incline towards the positionshown in phantom in Figure 1.

Assuming that the desired volume of air is produced for a given speed ofrotation with the fan blade approximately half way between Vthe positionshown in phantom and the position shown in full line, it will beappreciated that as long as the speed of rotation is maintained, aconstant volume of air will be produced.

However if a relatively heavy stand of grain is encountered, the machinewill perforce slow down due to the loading of the threshing cylindersand the like. This causes a slowing down in the speed of rotation of thefan thereby decreasing the air pressure upon the surfaces of the blades.Assuming that pin 41 has moved inward in 39 from its limiting positionshown in Fig. l, these circumstances permit spring 50 to force rod 40leftwardly slightly with reference to Figure l thus causing the rollers35 to turn the trunnion gear 20 in a direction to move the bladestowards the position shown in full line in Figure 2, thus increasing thevolume of air displaced by the blades and bringing it back to theoriginal volume of air being displaced prior to the slowing down of themachine.

Conversely if a relatively light stand of grain is encountered, themachine will tend to speed up thus increasing the air pressure upon thesurfaces of the blades which will cause them to move towards thedirection shown in phantom in Figure 2. This will rotate the trunniongear and the cams against rollers 35 and force the rollers together withhousing 31 rightwardly with respect to Figure l and against pressure ofspring 59. It will be appreciated that the design of the blades and theupper and lower limits of the speed of rotation thereof should be suchthat the aerodynamic air pressure effect is always greater than theinherent centrifugal effect in order that the said aero-dynamic effectcan control the angular relationship of the blade thus maintaining theconstant air volume desired.

In both of the foregoing examples, it will be appreciated that thetrunnion gear 20 although freely rotatable upon shaft 2, is not capableof endwise movement due to 4 the provision of a thrust race 54 betweenthe hub of the trunnion gear and the hub 5 of the spider.

From the foregoing it will be appreciated that a constant volume of aircan be maintained within limits irrespective of the speed of rotation ofthe fan unit.

Since various modifications can be made in my invention as hereinabovedescribed, and many apparently widely different embodiments of same madewithin the spirit and scope of the claims without departing from suchspirit and scope, it is intended that all matter contained'in theaccompanying specification shall be interpreted as illustrative only andnot in a limiting sense.

What I claim as my invention is:

l. A fan adapted to automatically maintain a given volume of air withinlimits, comprising in combination a drive shaft journalled for rotationbetween bearing, a spider casing secured to said drive shaft androtatable therewith, a set of fan blades, shafts for each of said fanblades mounted around the perimeter of said spider casing for limitedrotative movement relative thereto, trunnion means journalled forrotation upon said shaft, means cooperating between said trunnion meansand said fan blade shafts whereby relative movement of said tunnionmeans provides relative movement to said fan blades, means on said shaftmounted for limited endwise movement thereon engaging said trunnionmeans and adapted to rotate said trunnion means within limits, andadjustment means externally of said spider casing adapted to pleselectsaid limits of rotation on said trunnion means, said means cooperatingbetween said trunnion means and said fan blade shaft including a segmentgear secured to each of said fan blade shafts adjacent the apex of saidsegment gear, said trunnion means taking the form of a gear for bearingrotation on said shaft, said gears on said fan blade shalt engaging saidtrunnion gear.

2. The device according to claim l in which said gears on said fan bladeshaft take the form of segment gears secured to each of said fan bladeshafts adjacent the apex of said segment gears.

3. The device according to claim l in which said means on said shaftmounted for limited endwise movement thereon includes a carriersurrounding said shaft, and being in splined relationship therewith forsaid endwise movement, rollers journalled for rotation around one end ofsaid carrier in a plane parallel to the longitudinal axis of said shaft,and cam faces on one side of said trunnion means engageable by saidrollers.

4. The device according to claim l in which said ad justment meansincludes an annular groove within said means adapted to rotate saidtrunnion means, an endshifting ring freely mounted within said groove, arod extending from said ring, a guide cylinder for said rod, and springmeans reacting between said rod and said cylinder, and an adjusting nutwithin one end of said cylinder for adjusting the tension of saidspring.

5. The device according to claim 3 in which said adjustment meansincludes an annular groove within said means adapted to rotate saidtrunnion means, an end-shifting ring freely mounted within said groove,a rod extending from said ring, a guide cylinder for said rod, andspring means reacting between said rod and said cylinder, and anadjusting nut within one end of said cylinder for adjusting the tensionof said spring.

6. The device according to claim 2 in which said means on said shaftmounted for limited endwise movement thereon includes a carriersurrounding said shaft, and being in splined relationship therewith forsaid endwise movement, rollersjournalled for rotation around one end ofsaid carrier in a vplane parallel to the longitudinal axis of saidshaft, and cam faces on one side of said trunnion means engageable bysaid rollers.

.7. The device according to claim 2 in which said adjustment meansincludes an annular groove within said means adapted to rotate saidtrunnion means, and endshifting ring freely-mounted within said groove,a rod extending from said ring, a guide cylinder for said rod, andspring means reacting between said rod and said cylinder, and anadjusting nut within one end of said cylinder for adjusting the tensionof said spring.

8. The device according to claim 6 in which said adjustment meansincludes an annular groove within said means adapted to rotate saidtrunnion means, an endshifting ring freely mounted within said groove, arod extending from said ring, a guide cylinder for said rod, and springmeans reacting between said rod and said cylinder, and an adjusting nutwithin one end of said cylinder for adjusting the tension of saidspring.

References Cited in the le of this patent UNITED STATES PATENTS MoranDec. 4,

Strite Feb. 14,

Wagner Aug. 19,

Scofield Sept. 5,

Mader Aug. 21,

FOREIGN PATENTS Germany Nov. 7,

